This talk is designed for housestaff and cardiology fellows, with a an orientation to equipping these folks for the types of questions asked on internal medicine and cardiology boards.
Several schemes for estimated perioperative risk have been used over the years. Although perhaps the most subjective, the American Surgical Association/Dripps classification is still commonly used by anesthesiologists. The Goldman Index was the first risk stratification method to use modern statistical methods and identified 9 clinical factors which correlated with cardiovascular risk and death. A weight was assigned to each risk factor based on the strength of the statistical risk and it was possible, using this method, to assign a number of points and use this point score, generally to place a patient in one of four risk categories. Although popular at the time, this was based primarily on the data from a single hospital (Mass General) and was subsequently shown to underestimate risk in certain populations, including the elderly, obese and those with vascular disease. The Detsky Index was a take-off of the Goldman Index which empirically added a number of additional clinical characteristics known to be associated with perioperative risk. Recommended today, and the focus of the remainder of this presentation are the joint recommendations of the AHA and ACC.
The urgency with which surgery is required has been shown to be an important predictor of risk. In fact, studies have shown that surgery performed on an emergent basis is associated with a 3-5 times increased risk compared with the same surgery conducted on an elective basis. Beyond the issue of urgency is the degree of risk arising from the type/complexity of surgery. Listed on this and the next two slides are the three categories of surgical risk and associated procedures. In general, it is most critical to remember the high risk procedures listed here, as these lead to special patient handling in the recommended algorithm to be presented shortly …. Notice that virtually all vascular surgery is considered high risk.
Perioperative Assessment Stanley Kurek, DO, FACS Associate Professor of Surgery UTMCK Dept. of Surgery
Know when to perform stress testing preoperatively
Learn how to reduce risk perioperatively in those at higher risk
Key Points 1. Extensive testing is rarely needed to determine risk 2. Evaluation/Testing not needed if: a. Low risk surgery b. Good functional capacity and no cardiac symptoms c. No clinical risk factors
Key Points 4. Revascularization (surgery or PCI) should be considered only if standard indications are present 5. If PCI to be done, delay before non-cardiac surgery should be as follows: POBA: 14 days BMS: 30-45 days DES: > 365 days
Key Points 6. Cardiac complications (both ischemia and infarction) are often manifested by: a. Confusion, other MS changes b. Hypotension c. Dyspnea, heart failure 7. Cardiac complications tend to occur postoperatively and not intraoperatively, with a peak incidence on POD # 2-3
Key Points ST Depression Ref: Mangano, et al, JACC, 1991
Dripps/ASA Classification Class Systemic Disturbance Mortality* 1 Healthy patient with no disease outside of the surgical process <0.03% 2 Mild-to-moderate systemic disease caused by the surgical condition or by other pathologic processes 0.2% 3 Severe disease process which limits activity but is not incapacitating 1.2% 4 Severe incapacitating disease process that is a constant threat to life 8% 5 Moribund patient not expected to survive 24 hours with or without an operation 34% E Suffix to indicate an emergency surgery for any class Increased
Goldman Risk Index Ref: Goldman M, Caldera D, Southwick, et al: Multifactorial index of cardiac risk in non-cardiac surgical procedures. N Engl J Med 148:2120-2127, 1988.
ACC/AHA Guidelines J Am Coll Cardiol, 2007; 50:1707-1732
Stepwise Approach to the Pre-operative Evaluation
Stepwise Approach to Preoperative Cardiac Assessment Need for emergency noncardiac surgery Operating room Evaluate and treat per ACC/AHA Guidelines Vigilant perioperative and postoperative management Consider Operating Room Low Risk Surgery Active cardiac conditions No Yes Yes No Proceed with planned surgery Asymptomatic and good functional capacity Yes Proceed with planned surgery No Yes Manage based on clinical risk factors No
Manage based on clinical risk factors 3 or more clinical risk factors* 1 or 2 clinical risk factors* No clinical risk factors* Vascular Surgery Intermediate risk surgery Vascular Surgery Intermediate risk surgery Proceed with planned surgery Proceed with planned surgery with HR control or consider non-invasive testing Consider Testing *Clinical risk factors = known ischemic heart disease, compensated or prior HF, diabetes, renal insufficiency, cerebrovascular disease
Importance of Surgical Urgency Elective Surgery: Carried out at a time to suit the patient and surgeon Urgent Surgery: Carried out within 24-hrs of admission Emergency Surgery: Carried out within 2-hrs of admission or in conjunction with resuscitation Source: Evaluation of National Confidential Enquiry into Perioperative Deaths (NCEPOD) Non-Cardiac Surgery
Surgical Urgency? Key Point: Patients undergoing urgent or emergent surgery are at higher risk of postoperative complications and require closer surveillance postoperatively.
3 CRFs, poor functional capacity & vascular surgery (class IIa)
Nuclear stress testing
Which test to choose? Most ambulatory patients Abnormal resting ECG (dig, LVH) LBBB Unable to exercise Treadmill Stress Test Exercise echo or sestamibi DSE Adenosine sestamibi dipyridamole sestamibi
PCI before anticipated surgery Acute MI High Risk ACS High risk anatomy Stent and continued Dual-antiplatelet rx Bleeding risk of anticipated surgery Balloon angioplasty Bare-metal stent Drug-eluting stent 14 to 29 Days 30 – 365 Days > 365 Days Low Not low
Timing of Surgery After PCI Balloon angioplasty Bare-metal stent Drug-eluting stent < 14 days > 14 days < 30-45 days > 30-45 days < 365 days > 365 days Delay Surgery with ASA Delay Delay Surgery with ASA Surgery with ASA
Beta blockers required in recent past to control symptoms of angina or patients with symptomatic arrhythmias or hypertension
Patients at high cardiac risk owing to the finding of ischemia on preoperative testing who are undergoing vascular surgery
Patients undergoing vascular surgery and with identified CAD
Vascular surgery and multiple cardiac risk factors
Moderate or high risk surgery and multiple cardiac risk factors
Key Point: if known or suspected CAD and undergoing moderate or high risk surgery, use a beta blocker!
Perioperative Nitrates? Dodds, et al. Anesth. Analg. 1993;76:705-13 ACC/AHA 2007 Recommendations: Nitrates Class I: None Class IIa: None Class IIb: Can consider in context of anesthetic plan and patient hemodynamics
Perioperative Statins Hindler, et al. Anesthesiology 2006;105:1260-72 ACC/AHA 2007 Recommendations: Statins Class I: Patients currently taking statins Class IIa: Patients undergoing vascular surgery Class IIb: Patients with at least 1 clinical risk factor undergoing intermediate risk surgery
Low risk patients (bileaflet Aortic valve, no risk factors)
Stop warfarin 48-72 pre-op
Resume 24 hrs post-op
High risk patients (mitral valve, aortic valve + any risk factor)
Bridge with UFH, starting when INR < 2
Can anticoagulation be stopped in the patient with a mechanical heart valve? Risk factors: AF, previous thromboembolism, LV dysfunction, hypercoagulable state, older generation valve, mechanical tricuspid valve, more than one mechanical valve